Off-peak water heating system



Dec. 16, 1941. H. M. BIEBEL 2,266,149

OFF-PEAK WATER HEATING SYSTEM Filed March 27, 1941 W 4 INVENTOR.

HERMAN MB/EBA'L BY 2M ATTORNEY Patented Dec. 16 1941 UNITED STATES PATENT. OFFICE,

OFF-PEAK WATER HEATING SYSTEM Herman M. Biebel, 111., asslgnor to McGraw Electric Company, Elgin, 111., a corporation of Delaware App fi tion March 27, 1941, Serial No. 385,449

6 Claims. (01.219-39) tem embodying my invention or will be pointedout hereinafter in the course of such description or set forth in the appended claims.

In the single sheet of drawings:

Figure 1 is a view, in vertical section, through an ordinary hot water tank having associated therewith a control system for the electric heater thereof, embodying my invention, and,

Fig. 2 is a view of a modified form of contact means embodying my invention.

I have illustrated a domesticv hot water tank I I which may have provided thereon a cold water inlet pipe I3 and a hot water outlet pipe I5. The tank may be surrounded by a mass of heat insulating material I] which may be properly supported and protected by an outer casing I9.

I provide an electric heater 2| which is shown schematically or generally only and if this heater is to be mounted on the tank against the outer surface thereof, it may be positioned in a tunnel 23, all in a manner well known in the art.

I provide a plurality of thermal switches responsive to the temperature of the water at selected difierent points or heights of the tank and I have shown four such switchesnumbercd 25, 21, 29 and 3|. These thermal switches are shown generallyonly as including bimetal bars 33, 35, 31 and 39, each having one end thereof fixedly mounted on a suitable contact member so applied to or mounted'on the tank as to receive heat therefrom. Therespective thermal switches include fixed contact members 4|, 3, 45 and 41 adapted to be engaged by and disengaged from changes may be made in the mechanical details of the drive within the province of my invention which contemplates causing rotation of a certain element, namely a contact member, once in twenty-tour hours,

The worm gear 59 may be mounted on a shaft 6| which may have mounted thereon a circular contact member insulated therefrom by suitable means. The member 63 is here shown as ,being a. cylinder having a uniform outer radius over the major portion, substantially two-thirds I desire it to be understood that this showing of a continuously operative timing means is repreof its periphery, while a second portion is of larger outer radius and has a leading edge 61 which extends angularly relatively to the axis of member 63. While I have not shown any supporting bearings for shaft 5| it is to be understood that such bearings will be supplied.

I provide a contact arm or brush 59 which is shown as being adapted to engage a portion 18 of member 53 having a uniform outer radius. I also provide three additional brushes or contact arms ll, 19 and 15 which are suitably supported in side-by-side or in longitudinally spaced positions to be adapted to engage, in sequence, the leading edge 51 of the portion 55. It is to be understood that the trailing edge 11 of portion 65 extends substantially axially of the shaft 5|.

The heater 2| is controlled by an electromagnetic switch or contactor 19 including a coil 8| and a magnetizable core'. member 83. A main contact bridging member, and an auxiliary contact bridging member 81 are suitably connected with core 83 to move therewith. The bridging member 85 is adapted to engage with and be disengaged from fixed contact members 89 while the auxiliary bridging member 81 is adapted to engage with and be disengaged from fixed contact members 9 I.

Supply circuit conductor 53 is connected by a conductor 93 with brush 69. Brush H is connected by a conductor 95 with fixed contact member 41 of the uppermost thermal switch 3| and I wish to here point out that with clockwise rotation of member 63 brush H will be the first of the three brushes to engage the contact surface 65. I wish to point out further that while I have shown member 63 as being made of electric conducting material, I can make the portion other than element 65 of non-conducting material and merely mount thereon an electric conducting surface 65 of the hereinbefore described type.

Brush 13 is connected by a conductor 91 with fixed contact member 45 of the second uppermost sentative only and it is to be understood that 55 thermal switch 29. Brush l5 isconnected by a conductor 99 with fixed contact-member d3 of thermal switch 21. One terminal of coil 8| is connected by a conductor |I with the fixed contact supporting bimetal bar 35 of thermal switch 21 and a conductor I03 connects conductor |0I with the fixed supports of bimetal bars 31 and 39. The other terminal of coil 8| is connected by a conductor I05 with one terminal of coil 2| and with the fixed support of bimetal bar 33 of the lowermost thermal switch 25. The other terminal of heater 2| is connected by a conductor I01 with-one of the fixed contact members 89 while the other fixed contact member 89 is connected by a conductor I09 with supply circuit conductor 53. Fixed contact member 4| of the lowermost thermal switch 25 is connected by a conductor II I with the other supply circuit con-'- ductor 55.

For illustrative purposes it may be pointed out that the maximum peripheral extent of the contact surface 65 is equal substantially to that of the length of an off-peak periodand I have shown this as being equal to substantially eight hours. The position in which contact surface I55 is shown is that which it would occupy just a short time before .10 ,P. M. on the assumption that the utility supplyingcurrent to energize my improved system would'consider that an oil-peak period extended from substantiall P. M. to 6 A. M.

As soon as brush II engages the leading edge 61 of contact member 65 and, assuming that the the closed lowermost thermal switch 25 and from there through conductor II I to the other supply circuit conductor 55. It .will be noted that this holding circuit is entirely independent of brush II and the contact surface 65.

Let it now be assumed that the uppermost thermal switch 3| was in the position shown in Fig. 1 of the drawing at the start of an off-peak period, that is, at least the uppermost part of the tank was filled with hot water but that the second thermal switch 29 was subject to cold water when it would be in closed position instead of the position shown in Fig. 1 of the drawing. The same energizing circuit through coil 8| of the thermally actuable switch I9 will be established at a later time after the start of an off-peak period by engagement of second brush 13 with the contact surface 05 and this energizing circuit will include conductor 91 and closed switch 29 instead Y start of an oil-peak period or until brush I5 enbimetal bar 39 is in engagement with fixed contact 41, an energizing circuit through coil 8| will be established substantially as follows: From supply circuit conductor 53 through conductor 93 andbrush 69 to the contact member 53 and from there through the brush 1| and conductor 95 and through the engaged'parts of the uppermost thermal switch 3|, through conductors I03 and MI,

through coil 8|, through conductor I05 and the closed lowermost thermal switch 25 and from there through conductor I II to the other supply- '19 substantially at the start of an off-peak period. It is to be further noted that when the uppermost thermal switch 3| is closed because of being subjected to cold water, all of the thermal switchesmounted on thetank will also be closed.

of the conductor. 95 and closed switch 3|.

Let it be assumed that the tank contains a still greater amount of hot water at the start of an off-peak period so that the two uppermost thermal switches 3| and 29 are subject to hot water but that thermal switch 21 is subject to cold water. In-this case energization of the heater 2| will be delayed for a still longer time after' the ga es contact surface 65 when a similar energizing circuit through coil M will be established, this circuit including conductor 99 and the closed switch 21 instead of the similar conductors and switches 'hereinbefore mentioned as constituting parts of different energizing circuits for coil 8|.

Let it be assumed, for purposes of illustration, that the tank contained a relatively large amount of hot water at the start of an ofi-peak period and that substantially all of the water in the tank was heated or became hot say an appreciable time before the end of an off-peak period at which time all of the brushes II, I3 and I5 were still in engagement with the contact surface 65. it is therefore evident that all of the thermal switches would be in their open position with consequent deenergization' of heater 2| which condition insofar as the contactor I9 and the thermal switches are concerned, is that shown in Energization of the coil 8| through the circuit above described will cause energization of heater 2| through a circuit substantially a follows:

From supply circuit conductor 53 through con-;

2| and from there through the closed lowermost thermal switch 25 and from there through conductor III to the other supply circuit conductor 55. This operation will therefore start heating of the water-in the tank at substantially the start of an o'fi-peak period.

I provide also a holding circuit for the coil 8| which may be traced as follows: From supply circuit conductor-'53 through conductors I09 and H3 to one of the auxiliary fixed contact members 9|, from there through the contact bridging member 81 and the other contact 9|, through a conductor I I5 to one of the terminals of coil 8|, through coil 8| and conductor I05 to and through Fig. 1 of the drawing.

Let it now be assumed that such an amount of hot water is withdrawn,. shortly before the end of an off-peak period, as will subject the two lowermost thermal switches 25 and 21 to cold water with attendant closing of these switches. The 'contactor l9will have its coil 8| reenergized through the action of the second lowermost thermal switch 21 and the brush I5, which latteris still in engagement with contact surface because the end of an oil-peak period has not yet arrived. Reenergization of theheater -2| will therefore be effected and since the holding circuit for the coil 8| is independent of the brush or brushes engaging a continuously movable contact surface, energization of the heater 2| will conand permit the contactor to move to the position,

shown in the full lines in' Fig. 1 of the. drawing. My system'therefore provides main heater controlling switching means effective to continue or prolong the energization of the heater beyond the end of an oil-peak period-should the conditions hereinbefore set forth. occur.

magnetic switch for It may happen that the demand for hot water on any one day is greater than ordinarily occurring and the user might wish to efiect energization of the heater 2I and for this purpose I provide a small push button switch III normally open but adapted to be moved into closed position by the user. One terminal of switch II! isconnected by a conductor H9 to conductor IIII closure of switch I I! will therefore effect energization of the heater 2I irrespective of the operating position of the timing means hereinbefore described and it is further evident that this energization of heater 2I will continue until the tank is again filled with hot water.

Referring now to Fig. 2 of the drawing, I have there shown a modified form of continuouslymovable contact surface and only those parts differing from those shown in Fig. 1 are here illustrated. I provide a flat relatively thin disk I23 of electric insulating material having mounted thereon an electric conducting contact surface I25 which may be electrically connected to shaft GI on which disk I23 is suitably mounted. I provide three brushes which, for convenience, are given numbers II, I3 and I5 as in Fig. 1 of the drawing, and which are so supported relatively to the leading edge I21 of contact surface I25 that brush II will engage the leading edge I21 of member I25 at substantially the start of an offpeak period. Brush I3 will engage member I25 later and brush I5 will engage contact surface I25 at a still later time thus providing two fixed delays for energization of coil 2| the operation of my system including the parts shown in Fig. 2 of the drawing being therefore substantially the same as was hereinbefore set forth for the contact surface 65 in Fig. 1 of the drawing.

extending leading edge movedcontinuously by said timer, a plurality of fixed contact brushes adapted to be engaged by said plate in predetermined time sequence, a plurality of thermal switches located at different heights on the tank, electric connections between said thermal switches, said contact brushes and said electromagnetic switch to cause different delay times after the start of an oil-peak period in the energization of the electromagnetic switch and of the heater in accordance with the position of the thermal switch on the tank which is subject to cold water.

3,. In an ofi-peak water heating system for a tank having a single electric heater near the lower end .of the tank, an electromagnetic switch for said heater, a continuously operative timer, an electric conducting plate having an angularlyextending leading edge moved continuously by said timer, a plurality of fixed contact brushes adapted to be engaged by said plate in predetermined time sequence, a plurality of thermal switches located at different heights on the tank, electric connections between said thermal switch'es, said contact brushes and said electromagnetic switch to cause difierent delay times after the start of an ofi-peak period in the energization of the electromagnetic switch and of the heater in accordance with the position of the thermal switchon the tank which is subject to cold water and a thermally actuable heater control switch to cause deenergizationof the heater when substantiallyall of the water in the tank is hot.

Various modifications may bemade in-the system embodying my invention as herein shown and described and all such modifications clearly coming within the scope of the appended claims are to be considered as being covered thereby.

I claim as my invention:

1. In an ofi-peak water heating system for a tank having a single electric heater, an electrosaid heater, a continuously operative timer, an electric conducting plate adapted to be moved by said timer, a plurality of fixed contact brushes adapted to be engaged by said plate, a plurality of thermal switches located at different heights on the tank, electric connections between said thermal switches, saidcontact. brushes and said electromagnetic switch to cause energization of the electromagnetic switch and of the electric heater a period of time after th start of an off-peak period, which period increases with the amount of hot water in the tank.

2. In an ofi-peak water heating system for a tank having a single electric heater near the lower end of the tank, an electromagnetic switch for said heater, a continuously operative timer, an electric conducting plate having an angular 4. In an ofif-peak water heating system for a tank having an electric heater, an electromagnetic switch for said heater, a continuously operative timer, an electric conducting plate adapted to be moved by said timer, a plurality of fixed contact brushes adapted to be engaged by said plate, a plurality of thermal switches located at different heights on the tank, electric connections between said thermal switches, said contact brushes and said electromagnetic switch to cause different delay times after the start of an off-peak period in the energization of the electromagnetic switch and of the heater in accordance with the position 01' the thermal switch on the tank which'is subject tocold water and a thermally actuable heater control switch to cause deenergization of the heater when substantially all of the water in the tank is hot and to cause reenergization or said heater in case of withdrawal of hot water before the end of an oilpeak period suflicient to subject at least the second-lowermost thermal switch to cold water.

A System as set forth in claim 4 and including a normally open switch movable into momentarily closed position to cause energization of said electromagnetic switch and of said heater at any desired time during an on-peak period in case less than all of the water in the tank is 

